Research Goal: To identify the optimal dose of telephone-delivered problem solving therapy (PST) that improves medication adherence (measured using electronic pill containers) in non-adherent post-Acute Coronary Syndrome (ACS) patients. Career Development Goals: (1) to increase my expertise in Phase I behavioral medicine trial design and execution. (2) to increase my expertise in conducting and supervising systematic reviews of behavioral medicine interventions. This expertise will allow me to mentor beginning clinical researchers in the full range of clinical trial designs required to effectively test behavioral interventions. Mentoring Plan: I am proposing a series of didactic courses, tailored mentoring, and structured research experiences to increase the independence of my trainees' research careers. I will work with trainees from a variety of professional backgrounds, thus enriching the science and mentoring for the entire group, as well as for myself and my colleagues. Research Plan: As many as 20% of post ACS patients are not adherent to their prescribed medications, even in the 30 days immediately following an ACS event. These patients have an increased mortality rate compared to adherent patients. However, effective, inexpensive, generalizable adherence interventions remain unavailable. I will apply an innovative behavioral theory-Behavioral Activation-to the problem of non-adherence, using a randomized, controlled, dose (frequency)-escalating telephone intervention to determine the Minimally Effective Dose (MED) and the Maximally Tolerated Dose (MTD) for MEMS assessed aspirin adherence. Cohorts of 12 post-ACS patients will be randomized to Usual Cardiology Care or to PST sessions for 30 days. PST frequency will increase from 2 to10 sessions for each cohort. The MED will defined as the dose at which a 20% adherence difference is detected between the two conditions, and MTD will be defined as the dose at which 33% (2/6) patients have missed one PST session. This research will allow my trainees and me to conduct an early phase behavioral trial, interact extensively with nonadherent patients and cardiologists, so as to better understand this challenging behavioral problem.